Ammonia gas sensor based on the frequency-dependent impedance characteristics of ultrathin polyaniline films

Abstract

This paper describes a variety of experiments that reveal the potential application of impedance spectroscopy (IS) measurements to enhance performance of ultrathin polyaniline (PANI)-based films on flexible substrate to control ammonia gas exposure in the 0–20ppm range. Further, the device is mechanically robust for making electrical contact without lithography. We have employed the IS technique to proper adjust the optimal operation frequency of an easy-to-process, inexpensive and user-friendly PANI-based resistometric detectors in which drift current and delay problems related to electrode effects and dielectric absorption of PANI are insignificant. These requirements place emphasis upon the material and device configuration, and the range of frequencies from 10 to 100Hz corresponds to the ideal working region to operate the device to unify sensibility inside 5%, reproducibility, linearity, stability and low response time (<1min). These results are as efficient as those obtained using a more expensive commercial apparatus and can rival the affordability of traditional sensors. Linear Discriminant Analysis (LDA) and K-Means clustering confirmed that the device has the capacity to recognize ammonia concentration around 20ppm with total accuracy of 95%. Our study provides evidence of a new way to improve the performance of PANI-based sensors that can potentially be employed to monitor the environment of livestock buildings, for example.